Me: “…if I go to Coles and buy my own soy milk, will you make it with soy?”

Juice girl: “I have to check…yes, that’s okay.”

I go to Coles, purchase a carton of soy milk, then hand it to the juice girl. My dream of a smoothie with soy milk—as advertised—was realised. No discount for supplying my own ingredients. (I did get the remainder of the milk back though.)

I’ve had a similar experience at a small pizza place.
They had a sign out the front proclaiming “Any small pizza” for a certain price during the daytime.
I went in to order my preferred pizza, and they said “oh no, that offer only applies to the marguerita.” I argued with them for a little while about the definition of “any pizza” but they just simply weren’t willing to honour it.
Totally lame.